One of the most important tasks for modern hearing aids is to provide improvement in speech intelligibility in the presence of noise. For this purpose, beamforming, especially adaptive beamforming, has been widely used in order to suppress interfering noise. Traditionally, the user of a hearing aid is given the possibility of changing between a directional and an omni-directional mode in the hearing aid (e.g. the user simply changes processing modes by flipping a toggle switch or pushing a button on the hearing aid to put the device in the preferred mode according to the listening conditions encountered in a specific environment). Recently, even automatic switching procedures for switching between directional and omni-directional modes have been employed in hearing aids.
In hearing aids, omni-directional perception by the user may be preferred over a directional mode for relatively quiet listening situations due to the fact that in situations, where any background noise present is fairly low in amplitude, the omni-directional mode should provide a greater access to the full range of sounds in the surrounding environment, which is intended to provide a greater feeling of “connectedness” to the environment, i.e. being connected to the outside world. The general preference for omni-directional processing when the signal source is to the side or behind the listener is predictable. Further, by providing greater access to sound sources that the listener is not currently facing, omni-directional perception may improve recognition for speech signals arriving from these locations (e.g., in a restaurant where the server speaks from behind or from the side of the listener). This benefit of omni-directional perception for target signals arriving from locations other than in front of the listener will be present in both quiet and noisy listening situations.
Binaural beamforming is known in the art. Currently, most beamformers are designed to process the multiple signals from the two hearing aids to achieve the best possible Signal-Noise-Ratio.